1. Field of the Invention
The present invention relates to digital image photography in diverse complex apparatuses having a function of photographing a digital image, including digital cameras, as well as mobile communication terminals having a camera module. More particularly, the present invention relates to a method for photographing a panoramic image and the plurality of images making up the panoramic image.
2. Description of the Related Art
In general, an image capture unit has a function of obtaining an image in a digital image photographing apparatus, and can obtain an image formed within a focal length of a lens thereof. Here, the obtained image is within a range of the viewing angle (between about 30° to 50° for general cameras), which is smaller than an actual human visual angle (between about 150° to 200°).
A conventional method of photographing multiple images includes acquiring the images while properly changing the viewing angle, and inter-connecting the photographed images in sequence to reorganize them into one consecutive image, thereby obtaining a picture with a viewing angle similar to or larger than the human visual angle. Such a conventional method is called a panoramic image photographing method.
In a panoramic image photographing mode, the conventional digital image photographing apparatus captures several images to be inter-connected horizontally or vertically, and then stores them in a memory. The images stored in the memory are provided to an appropriate interior/exterior image processor later, and are inter-connected into one consecutive image. At this time, in order to eliminate color differences and image discords at the boundaries between the images, digital image photographing apparatuses photograph multiple images with sufficient overlap between their boundaries, and then align the images by adjusting their boundaries. Thereafter, they perform image processing, including stitching and bending. Through this process, a single image including naturally inter-connected multiple images is obtained.
Accordingly, high priority in photographing a panoramic image is accorded to the capture of such images being aligned as accurately as possible. To this end, an accessory apparatus, such as a tripod, is usually used in manual photographing by a user. Recently, a method has been suggested in which a corresponding photographing apparatus is mounted on a tripod or the like, and the mounted photographing apparatus is rotated according to respective images in panorama photographing. An example of such a method is disclosed in Korean Patent Application No. 2003-0052444 filed on Jul. 29, 2003, entitled “Camera And Method for Photographing Panorama Picture” the application of which is Samsung Techwin Co. Ltd., and the inventor of which is BAE, Sung-cheol. Further to the above-described methods, an apparatus having a function of detecting a rotation angle may be additionally mounted on the corresponding photographing apparatus, and a user sets the rotation angle of the photographing apparatus in advance so that the respective images are photographed by rotational displacement over the rotation angle of the photographing apparatus pre-set by the user in panorama photographing, of which a method has been also suggested.
Furthermore, in order to align the respective images more accurately when photographing panoramic images without mounting an accessory element or additional hardware on the corresponding photographing apparatus, a method has been provided in which the partial region of the border of a previously photographed image is represented appropriately overlapping with the current image for photographing when photographing respective images, so that the user can control an appropriate position for photographing by adjusting the pre-photographed image with the current photographing image. An example of such the method is disclosed in US Publication No. 2004/0189849 filed on Mar. 31, 2003, entitled “Panoramic Sequence Guide” in the name of inventor Gregory V Hofer.
Photographing the panoramic image requires increased complexity and proficiency versus photographing a general single image, and this process has long had a need for better and more convenient solutions for manipulating and photographing images.
Meanwhile, FIG. 1 is a view illustrating relation between respective photographic images that make up a panoramic image. In a case where a camera obtains an image in such a manner that it rotates θ degrees at a horizontal direction, the camera converts a real three-dimensional image, such as a first subject or a second subject, etc., to a first image or a second two-dimensional image so as to display it. In the case where such images are combined with each other so as to implement a picture, distortion is generated due to the different perspectives, so that it is difficult to estimate an overlapped portion between images different from each other. As a result, it is impossible to form a truly natural panoramic picture.
For example, in a case where the first image and the second image, which are obtained through a method illustrated in FIG. 1, are images of FIGS. 2A and 2B, respectively, and respective portions of the two images, which are obtained by photographing the same area, are overlapped with each other, as shown in FIG. 3, the portions, which are obtained by photographing the same area, aren't equal to each other, and the overlapping portion is distorted.
Accordingly, a method for generating a more accurate panoramic picture in such a manner that respective portions of a plurality of images, which are obtained by photographing the same area, are equal to each other.